The present invention relates to circuit chip mounted cards and circuit chip modules, and more particularly to a circuit chip mounted card and a circuit chip module with increased reliability, reduced manufacturing cost and the like.
Non-contact type IC cards are used for the gate of the ski lift, the gate at the station, automatic sorting of parcels and the like. A conventional non-contact type IC card is exemplified in FIG. 12. An IC card 2 shown in FIG. 12 is an IC card of a single coil type, and includes a coil 4, capacitors C1 and C2 and an IC chip 8.
Capacitors C1 and C2 and IC chip 8 are included in a film substrate formed of synthetic resin. The substrate including capacitors C1 and C2 and IC chip 8 are referred to as a tab (tab: tape automated bonding) 10.
FIG. 13A is a cross sectional view showing IC card 2. A core member 12 of synthetic resin is interposed between surface layer materials 14 and 16. Tab 10 including capacitors C1 and C2 and IC chip 8 is fixed to surface layer material 14 which is exposed to a cavity 18 in core member 12. A connection of tab 10 and IC chip 8 is covered with a sealing material 9 of epoxy resin or the like.
Coil 4 is arranged between surface layer material 14 and core member 12. A wire 20 connects coil 4 and tab 10.
FIG. 13B is a circuit diagram showing IC card 2. IC card 2 receives an electromagnetic wave transmitted from a reader/writer (reading/writing apparatus, not shown) by a resonance circuit 22 formed of coil 4 and capacitor C1 as a power source. It is noted that capacitor C2 is used for smoothing power.
In addition, a control portion (not shown) provided in IC chip 8 decodes information transmitted by the electromagnetic wave for response. The response is performed by changing an impedance of resonance circuit 22. The reader/writer obtains a content of the response by detecting a change in an impedance (impedance reflection) of its own resonance circuit (not shown) due to the change in the impedance of resonance circuit 22 on the side of IC card 2.
Thus, the use of IC card 2 allows data communication in a non-contact state without a power supply source in the card.
However, the above described conventional IC card suffers from the following problem.
In IC card 2, coil 4 and tab 10 must be connected by wire 20. On the other hand, IC card 2 is often put in a wallet or a pocket of a trouser, where it is subjected to considerable bending, twisting and pressing forces. However, a thickness t of IC card 2 shown in FIG. 13A is standard and not so thick. Thus, it is not provided with a significant rigidity against such bending, twisting and pressing forces. Therefore, if IC card 2 is subjected to a significant bending force or the like, a considerable deflection is caused. Such deflection may result in a breakage of wire 20 or disconnection of wire 20 and coil 4 or tab 10. In addition, wire 20 may not be well connected to coil 4 or tab 10.
Further, to ensure a space for coil 4, tab 10 must restrictively be positioned. Thus, in some cases, tab 10 must be provided in a position where a significant deflection is caused. This may result in significant deformation of IC chip 8. Accordingly, IC chip 8 is cracked and does not well function as an IC card.
As described above, the conventional IC card is difficult to handle and lacks in reliability.
Moreover, as coil 4 and tab 10 must be connected by wire 20, complicated assembly is involved, thereby increasing a manufacturing cost.
In addition, provision of capacitors C1 and C2 and the like in tab 10 further increases the manufacturing cost.
An object of the present invention is to provide a circuit chip mounted card with high reliability and low manufacturing cost by overcoming the aforementioned problem related to the conventional card.
According to one aspect, the circuit chip mounted card of the present invention which achieves the above object includes: an antenna for communication utilizing an electromagnetic wave; a processing portion performing a process for communication; a first circuit chip including at least a portion of a processing portion and having a terminal; and a second circuit chip including the antenna and the remaining portion of the processing portion and having a terminal, and is characterized in that the terminals are electrically connected by stacking the first and second circuit chips in a direction of thickness of the card.
According to the present invention, such structure eliminates the need for arranging the interconnection outside the circuit chip because a function of communication is achieved simply by stacking two circuit chips including the functions of the processing portion and antenna. Thus, insufficient connection caused by external arrangement of the interconnection is avoided. Further, even if the deflection is repeatedly caused for the card, breakage of the external arrangement of the interconnection or accidental disconnection would be avoided.
In addition, as the antenna is included in the second circuit chip which is in turn stacked on the first circuit chip, the positional restriction of the circuit chip to ensure a space for the antenna is eliminated. Thus, the stacked circuit chips with a small area when viewed from above is provided in an arbitrary position where a significant deflection would not be caused. As a result, even when a significant force is applied to the card, the circuit chips would not significantly be deformed.
Further, as the interconnection needs not be externally arranged, assembly is extremely facilitated. Thus, reduction in the manufacturing cost is achieved. In addition, as the capacitor is also included in the circuit chip, the work for mounting the capacitor is not necessary. This results in further reduction in the manufacturing cost. Therefore, the circuit chip mounted card with high reliability and low manufacturing cost is achieved.
The circuit chip mounted card according to the present invention having the above described structure is obtained preferably by providing the terminal for the first circuit chip on the side of the second circuit chip, providing the terminal for the second circuit chip on the side of the second circuit chip such that it is opposite to the terminal for the first circuit chip, and directly connecting the first and second circuit chips in a stack.
Such structure allows two circuit chips to be readily connected to form a module using a conventional technique for connecting the terminals. Thus, further reduction in the manufacturing cost is achieved as workability during manufacture increases.
According to another aspect, a circuit chip mounted card of the present invention provided with an antenna for communication utilizing an electromagnetic wave and a processing portion performing a process for communication includes: a first base material; a second base material arranged in a direction of thickness of the card spaced from the first base material with a prescribed distance; a core member layer interposed between the first and second base materials; and a circuit chip module arranged in the core member layer. The circuit chip mounted card is characterized in that it is a composition of a first circuit chip including at least a portion of the processing portion and having a terminal and a second circuit chip including the antenna and the remaining portion of the processing portion and having a terminal arranged opposite to the terminal of the first circuit chip which are stacked and connected in a direction of thickness of the card through an anisotropic conductor to electrically connect the terminals.
According to the present invention, such structure allows two circuit chips to be securely connected with the anisotropic conductor interposed.
In most cases, an opening is provided in the circuit chip for external arrangement of the interconnection before the circuit chip is mounted in the card, which opening leads to an interconnection layer of aluminum or the like through a protection film on a surface. Thus, the aluminum of the interconnection layer may suffer from corrosion during a period from the manufacture of the circuit chip to mounting in the card and due to secular change after assembly. In the circuit chip mounted card according to the present invention, the first and second circuit chips can be connected through the anisotropic conductor after manufacture, as external arrangement of the interconnection is not necessary when they are mounted in the card. In other words, corrosion of the aluminum of the interconnection layer or the like is reduced as the first and second circuit chips are closely connected through the anisotropic conductor.
In a preferred embodiment of the circuit chip mounted card according to the present invention, a reinforcing member including a frame which is arranged to surround the first and second circuit chips in a direction of the face of the chip is provided in the card.
Such structure effectively increases rigidity of the card in vicinity of the circuit chip while ensuring a space for the stacked circuit chips. Thus, even if significant bending, twisting and pressing forces are applied to the card, the stacked circuit chips would not significantly be deformed. In other words, the circuit chip mounted card is provided with increased reliability.
According to one aspect, a circuit chip module of the present invention forming a card with a circuit including an antenna for communication utilizing an electromagnetic wave and a processing portion performing a process for communication includes: a first circuit chip including at least a portion of the processing portion and a terminal; and a second circuit chip including the antenna and the remaining portion of the processing portion and having a terminal, and is characterized in that the first and second circuit chips are stacked in a direction of thickness of the card to electrically connect the terminals.
Such structure of the circuit chip module according to the present invention enables a communication function to be performed only by a small circuit chip module. Thus, elements in the card can more freely be arranged. In addition, as a preliminary formed single module is merely involved for assembly, the manufacturing cost is further reduced with increased workability.
In a preferred embodiment of the circuit chip module according to the present invention, a resonance frequency of a resonance circuit including a capacitor provided inside the circuit chip and a coil for the antenna can be adjusted.
Such structure allows the capacitance or inductance of the resonance circuit to be adjusted after the capacitor and coil are formed in the circuit chip. Thus, the resonance frequency can be adjusted after formation of circuit elements though these circuit elements of the resonance circuit are all formed in the circuit chip.
More specifically, the circuit chip mounted card is provided with high reliability as the resonance frequency can be maintained at a prescribed level to some extent even if there is a variation in manufacturing conditions. Further, since a circuit chip corresponding to various resonance frequencies is obtained without changing a mask pattern for forming the circuit elements in a manufacturing process of the circuit chip, the manufacturing cost is not increased.
According to another aspect, a circuit chip module of the present invention is a composition of circuit chips including stacked first and second circuit chips, and characterized in that at least one of the first and second circuit chips is provided with a detour interconnection which electrically connects two terminals of the above mentioned one circuit chip and the detour interconnection electrically connects two terminals of the other circuit chip respectively connected to the two terminals.
With such structure, the circuit chip module according to the present invention can only perform an essential function when two circuit chips are connected. Thus, even when the circuit chip module is divided into two circuit chips, it is difficult to analyze the function by each terminal. A plurality of detour interconnections would further make it difficult to analyze the function. In other words, the circuit chip module with high security is achieved.